Flora of North America species comparison

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Quercus turbinella

Quercus phellos

grey oak, shrub live oak, Sonoran scrub oak, turbinella oak

willow oak
Habit Shrubs or small trees, evergreen or subevergreen, to 4 m. Bark light gray or brown, scaly. Trees, deciduous, to 30 m. Bark dark gray and smooth, becoming darker and irregularly fissured with age, inner bark light orange.
Twigs

brown to gray, 1-3 mm diam., usually tomentulose, sometimes glabrous, becoming glabrate.

reddish brown, 1-2 mm diam., glabrous.
Buds

brown, round to ovoid, 1-2 mm, minutely pubescent.

Leaves

blade elliptic or ovate, (1.5-)20-30 × (5-)10-15(-20) mm, thick, leathery, base cordate or rounded, margins planar or slightly crisped-undulate, coarsely 3-5-toothed or very shallowly lobed on each side, teeth spinose with spines 1-1.5 mm, secondary veins 4-8 on each side, apex acute or obtuse;

surfaces abaxially yellow or reddish, usually glaucous, minutely stellate-puberulent, adaxially grayish, glaucous, or yellowish glandular, glabrous or sparsely and minutely stellate-pubescent.

blade linear to narrowly elliptic, usually widest near middle, 50-120 × 10-25 mm, base acute, margins entire with 1 apical awn, apex acute;

surfaces abaxially pale green, glabrous, rarely softly pubescent, adaxially light green, glabrous.
Acorns

solitary or several, on axillary peduncle 10-40 mm;

cup hemispheric or shallowly cup-shaped, 4-6 mm deep × 8-12 mm wide, covering 1/4-1/2 nut, scales tightly appressed, ovate, moderately tuberculate, grayish or yellowish puberulent;

nut light brown, ovoid, to 20 × 11 mm, minutely puberulent or glabrate.

biennial;

cup shallowly saucer-shaped, 3-6.5 mm high × 7.5-11 mm wide, covering 1/4-1/3 nut, outer surface puberulent, inner surface light brown, pubescent, scale tips tightly appressed, acute;

nut ovoid to hemispheric, 8-12 × 6.5-10 mm, often striate, glabrate, scar diam. 4.5-6 mm.
Cotyledons

distinct.

Terminal

buds chestnut brown, ovoid, 2-4 mm, apex acute, glabrous.

Quercus turbinella

Quercus phellos
Phenology Flowering spring. Flowering spring.
Habitat Dry desert slopes, often in juniper and pinyon woodlands Of bottomland flood plains, also on stream banks, dunes, and terraces, and, occasionally, on poorly drained uplands
Elevation 800-2000 m (2600-6600 ft) 0-400 m (0-1300 ft)
Distribution
from FNA
AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Sonora, and probably n Chihuahua)
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; DC; DE; FL; GA; IL; KY; LA; MD; MO; MS; NC; NJ; NY; OK; PA; SC; TN; TX; VA
[WildflowerSearch map]
[BONAP county map]
Discussion

Formerly, California populations of what here is referred to as Quercus john-tuckeri have been included in the concept of Q. turbinella. Quercus john-tuckeri has subsessile fruit and noncordate leaf bases as opposed to the consistently pedunculate fruit and strongly cordate leaf bases of Q. turbinella. The two species seem to be no more closely related to each other than each might be to other southwestern oaks, and Q. john-tuckeri shares at least as many characteristics with Q. berberidifolia as with Q. turbinella. Thus, treatment of these two taxa as varieties of the same species is inappropriate.

Quercus turbinella forms putative hybrid swarms with Q. gambelii (see treatment), as well as with Q. grisea.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Individual trees with leaves softly pubescent abaxially may be classified as Quercus phellos forma intonsa Fernald; however, such leaves are known to occur on second-flush shoots from twigs bearing typical leaves.

Quercus phellos reportedly hybridizes with Q. coccinea (W. W. Ashe 1894); with Q. ilicifolia (= Q. ×giffordi Trelease) and Q. incana (E. J. Palmer 1948); and with Q. marilandica, Q. nigra, Q. pagoda (= Q. ×ludoviciana Sargent), Q. palustris, Q. rubra, Q. shumardii, and Q. velutina. D. M. Hunt (1989) cited evidence of hybridization also with Q. hemisphaerica, Q. imbricaria, Q. laurifolia, and Q. pumila.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 3. FNA vol. 3.
Parent taxa Fagaceae > Quercus > sect. Quercus Fagaceae > Quercus > sect. Lobatae
Sibling taxa
Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. coccinea, Q. cornelius-mulleri, Q. depressipes, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pacifica, Q. pagoda, Q. palmeri, Q. palustris, Q. phellos, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii
Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. coccinea, Q. cornelius-mulleri, Q. depressipes, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pacifica, Q. pagoda, Q. palmeri, Q. palustris, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii
Synonyms Q. dumosa var. turbinella, Q. subturbinella
Name authority Greene: Ill. W. Amer. Oaks 1: 37. (1889) Linnaeus: Sp. Pl. 2: 994. (1753)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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